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268 lines
8.6 KiB
Java
268 lines
8.6 KiB
Java
/*
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* Copyright (c) 2005, 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.nio.ch;
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import java.io.IOException;
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import java.nio.channels.ClosedSelectorException;
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import java.nio.channels.SelectionKey;
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import java.nio.channels.Selector;
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import java.nio.channels.spi.SelectorProvider;
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import java.util.ArrayDeque;
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import java.util.Deque;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.concurrent.TimeUnit;
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import java.util.function.Consumer;
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import static sun.nio.ch.EPoll.EPOLLIN;
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import static sun.nio.ch.EPoll.EPOLL_CTL_ADD;
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import static sun.nio.ch.EPoll.EPOLL_CTL_DEL;
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import static sun.nio.ch.EPoll.EPOLL_CTL_MOD;
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/**
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* Linux epoll based Selector implementation
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*/
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class EPollSelectorImpl extends SelectorImpl {
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// maximum number of events to poll in one call to epoll_wait
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private static final int NUM_EPOLLEVENTS = Math.min(IOUtil.fdLimit(), 1024);
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// epoll file descriptor
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private final int epfd;
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// address of poll array when polling with epoll_wait
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private final long pollArrayAddress;
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// eventfd object used for interrupt
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private final EventFD eventfd;
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// maps file descriptor to selection key, synchronize on selector
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private final Map<Integer, SelectionKeyImpl> fdToKey = new HashMap<>();
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// pending new registrations/updates, queued by setEventOps
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private final Object updateLock = new Object();
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private final Deque<SelectionKeyImpl> updateKeys = new ArrayDeque<>();
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// interrupt triggering and clearing
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private final Object interruptLock = new Object();
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private boolean interruptTriggered;
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EPollSelectorImpl(SelectorProvider sp) throws IOException {
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super(sp);
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this.epfd = EPoll.create();
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this.pollArrayAddress = EPoll.allocatePollArray(NUM_EPOLLEVENTS);
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try {
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this.eventfd = new EventFD();
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IOUtil.configureBlocking(IOUtil.newFD(eventfd.efd()), false);
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} catch (IOException ioe) {
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EPoll.freePollArray(pollArrayAddress);
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FileDispatcherImpl.closeIntFD(epfd);
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throw ioe;
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}
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// register the eventfd object for wakeups
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EPoll.ctl(epfd, EPOLL_CTL_ADD, eventfd.efd(), EPOLLIN);
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}
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private void ensureOpen() {
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if (!isOpen())
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throw new ClosedSelectorException();
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}
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@Override
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protected int doSelect(Consumer<SelectionKey> action, long timeout)
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throws IOException
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{
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assert Thread.holdsLock(this);
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// epoll_wait timeout is int
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int to = (int) Math.min(timeout, Integer.MAX_VALUE);
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boolean blocking = (to != 0);
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boolean timedPoll = (to > 0);
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int numEntries;
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processUpdateQueue();
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processDeregisterQueue();
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try {
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begin(blocking);
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do {
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long startTime = timedPoll ? System.nanoTime() : 0;
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numEntries = EPoll.wait(epfd, pollArrayAddress, NUM_EPOLLEVENTS, to);
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if (numEntries == IOStatus.INTERRUPTED && timedPoll) {
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// timed poll interrupted so need to adjust timeout
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long adjust = System.nanoTime() - startTime;
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to -= TimeUnit.MILLISECONDS.convert(adjust, TimeUnit.NANOSECONDS);
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if (to <= 0) {
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// timeout expired so no retry
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numEntries = 0;
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}
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}
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} while (numEntries == IOStatus.INTERRUPTED);
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assert IOStatus.check(numEntries);
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} finally {
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end(blocking);
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}
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processDeregisterQueue();
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return processEvents(numEntries, action);
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}
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/**
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* Process changes to the interest ops.
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*/
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private void processUpdateQueue() {
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assert Thread.holdsLock(this);
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synchronized (updateLock) {
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SelectionKeyImpl ski;
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while ((ski = updateKeys.pollFirst()) != null) {
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if (ski.isValid()) {
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int fd = ski.getFDVal();
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// add to fdToKey if needed
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SelectionKeyImpl previous = fdToKey.putIfAbsent(fd, ski);
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assert (previous == null) || (previous == ski);
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int newEvents = ski.translateInterestOps();
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int registeredEvents = ski.registeredEvents();
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if (newEvents != registeredEvents) {
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if (newEvents == 0) {
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// remove from epoll
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EPoll.ctl(epfd, EPOLL_CTL_DEL, fd, 0);
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} else {
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if (registeredEvents == 0) {
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// add to epoll
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EPoll.ctl(epfd, EPOLL_CTL_ADD, fd, newEvents);
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} else {
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// modify events
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EPoll.ctl(epfd, EPOLL_CTL_MOD, fd, newEvents);
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}
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}
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ski.registeredEvents(newEvents);
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}
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}
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}
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}
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}
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/**
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* Process the polled events.
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* If the interrupt fd has been selected, drain it and clear the interrupt.
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*/
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private int processEvents(int numEntries, Consumer<SelectionKey> action)
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throws IOException
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{
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assert Thread.holdsLock(this);
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boolean interrupted = false;
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int numKeysUpdated = 0;
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for (int i=0; i<numEntries; i++) {
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long event = EPoll.getEvent(pollArrayAddress, i);
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int fd = EPoll.getDescriptor(event);
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if (fd == eventfd.efd()) {
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interrupted = true;
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} else {
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SelectionKeyImpl ski = fdToKey.get(fd);
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if (ski != null) {
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int rOps = EPoll.getEvents(event);
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numKeysUpdated += processReadyEvents(rOps, ski, action);
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}
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}
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}
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if (interrupted) {
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clearInterrupt();
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}
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return numKeysUpdated;
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}
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@Override
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protected void implClose() throws IOException {
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assert Thread.holdsLock(this);
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// prevent further wakeup
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synchronized (interruptLock) {
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interruptTriggered = true;
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}
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FileDispatcherImpl.closeIntFD(epfd);
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EPoll.freePollArray(pollArrayAddress);
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eventfd.close();
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}
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@Override
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protected void implDereg(SelectionKeyImpl ski) throws IOException {
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assert !ski.isValid();
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assert Thread.holdsLock(this);
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int fd = ski.getFDVal();
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if (fdToKey.remove(fd) != null) {
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if (ski.registeredEvents() != 0) {
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EPoll.ctl(epfd, EPOLL_CTL_DEL, fd, 0);
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ski.registeredEvents(0);
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}
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} else {
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assert ski.registeredEvents() == 0;
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}
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}
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@Override
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public void setEventOps(SelectionKeyImpl ski) {
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ensureOpen();
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synchronized (updateLock) {
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updateKeys.addLast(ski);
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}
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}
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@Override
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public Selector wakeup() {
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synchronized (interruptLock) {
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if (!interruptTriggered) {
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try {
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eventfd.set();
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} catch (IOException ioe) {
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throw new InternalError(ioe);
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}
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interruptTriggered = true;
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}
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}
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return this;
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}
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private void clearInterrupt() throws IOException {
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synchronized (interruptLock) {
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eventfd.reset();
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interruptTriggered = false;
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}
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}
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}
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